Various magnetic recording systems such as hard disk drives utilize a write head to record data on a magnetic medium. Data to be recorded is provided to the write head coil as an alternating electrical current. The electrical current passes through a metallic coil wrapping around the write head, generating a magnetic field. The magnetization state of a pole tip in the write head is switched by the magnetic field. As the magnetized pole tip is passed over the magnetic storage medium, for example a spinning disc with a ferromagnetic coating, the magnetization of regions of the magnetic medium below the pole tip are altered and can later be read back to retrieve the data.
The write (recording) process is challenging at high speeds in magnetic recording. Conventionally, write current waveforms are delivered with pattern-independent levels and time-domain properties. However, the switching response of the magnetic system is not linear. The non-linearity between excitation and response signals is more pronounced as the data rate increases and the bit sequence includes more high frequency transitions. As a result, the global recording performance degrades, and data rate and areal density are limited.